code: def __init__(self, corpus, exclude_categories=[]):
      self.background_df = pd.DataFrame(
          corpus.remove_categories(exclude_categories)
          .get_term_freq_df()
          .sum(axis=1)
      ).rename(columns={0: "background"})
  
file_path: scattertext/scattertext/frequencyreaders/DefaultBackgroundFrequencies.py
imports: import pkgutil
  from io import StringIO
  import pandas
  from scipy.stats import rankdata
label_desc: Use image node_id 1 to create a new BackgroundFrequenciesFromCorpus object from inherited base classes: BackgroundFrequencyDataFramePreparer with example: obj = BackgroundFrequenciesFromCorpus(corpus, exclude_categories)